\begin{tikzpicture}
    \tkzDefPoints{0/0/O}
    \tkzDefPoint(160:1.5){A}
    \tkzDefPoint(20:1.5){B}
    \tkzDrawArc[thick](O,B)(A)
    \tkzLabelPoints[left](A)
    \tkzLabelPoints[right](B)

    % 1
    \tkzDrawSegment(A,B)

    % 2
    \tkzDefLine[mediator,K=.7](A,B)  \tkzGetPoints{C}{D}
    \tkzInterLC(C,D)(O,A)  \tkzGetFirstPoint{E}
    \tkzCompasss(A,C  B,C  A,D  B,D)
    \tkzDrawLine[add=0.1 and 0.1](C,D)
    \tkzDrawPoint(E)
    \tkzLabelPoints[right](C,D)
    \tkzLabelPoints[above right](E)
\end{tikzpicture}

